Verbal language, one of the hallmarks of human beings, enables us to express intricate thoughts, transmit cultural knowledge, and connect through generations. It is also one of the most studied domains in disciplines ranging from social sciences to neuroscience. Within this broad realm, the suffixing bias has turned out to be a particularly compelling phenomenon that continues to fascinate researchers as they attempted to provide an answer to the following question: Why do most world’s languages use suffixes more than prefixes to convey grammatical meanings like tense or number? And what is this related to? Our general cognition? Is it language-specific? Or even an accidental distribution caused by some random factors that are not related to language cognition per se?

At its core, the suffixing bias refers to a predisposition observed in various languages to indicate grammatical information by adding suffixes at the ends of words instead of prefixes at the beginnings. For example, plurality in English is marked by adding -s, as in cats, and tense is indicated with -ed, as in walked. In more precise terms, suffixing languages outnumber prefixing languages by a ratio of eight to one (Dryer, 2013). Due to this imbalance, a variety of theories have been proposed to address questions regarding the origin of the typological suffixing bias. Some argue for domain-general cognitive constraints, suggesting that the bias reflects broader perceptual or attentional mechanisms unrelated to language. Others claim that it is language-specific and emerges from structural and syntactic requirements inherent in human speech

Hupp, Sloutsky, and Culicover (2009) advocate the first model of this debate, which claims that humans naturally have a better processing capacity for sequences that vary at the end than at the beginning. This view assumes that, in general, our cognitive system is designed and adapted to process temporal sequences in such a way that it readily adapts to changes occurring at the end of a sequence. Researchers propose that this adaptability also applies to language processing. Supporting this theory, experiments involving mostly English speakers consistently showed that participants found sequences that were similar to those they had previously learned, but differed at the end, to be more similar than those that differed at the beginning. This tendency has been reported across various domains of stimuli, from shape sequences to musical notes, indicating an inherent cognitive bias rather than a phenomenon exclusive to language.

Recently, we have seen the emergence of theories that challenge this domain-general explanation. For instance, Martin and Culbertson (2020) tested Kîîtharaka speakers, a strongly prefixing Bantu language (e.g., -ntû, person; muntû, “one person”; antû, “more than one person/people”). In this experiment, native English and native Kîîtharaka speakers judged the similarity of sequences (of syllables or shapes) by comparing a target sequence with two altered versions: one differing at the start and the other at the end. Both groups decided which sequence was more similar to the target, allowing researchers to compare how native language influences perceptual preferences. Unlike English speakers, Kîîtharaka participants preferred sequences that differed at their beginnings, which was consistent with the structure of their native language. This finding thus highlights profound effects of linguistic experience on cognitive biases, and it suggests that preference for suffixing may not be universal. Furthermore, it shows the effects of language-specific factors, including the typological features of one’s native language.

Adding to this debate, a recent study by Ordin (2025) provides compelling evidence that the suffixing bias is specific to language. The study used a statistical learning paradigm, which is a method for examining how humans extract patterns from continuous streams of stimuli. Participants included Spanish monolinguals (a strongly suffixing language) and Basque-Spanish bilinguals (Basque uses both suffixes and prefixes). During the experiment, participants were exposed to streams of artificial words with embedded suffixes or prefixes. After familiarization, they completed tests assessing their ability to recognize these sequences.

While learning the recurrent artificial words, Spanish monolinguals took advantage of suffixes and exhibited a strong suffixing bias when they had to choose between a suffixed and a prefixed artificial word. Basque native speakers did not reveal any preference, and learnt prefixed words better than Spanish monolinguals, likely due to their exposure to Basque’s grammatical prefixes. This lack of suffixing bias among bilinguals suggests that their balanced exposure to both affix types in Basque neutralized the suffixing preference observed in monolinguals. This difference between groups highlights the role of linguistic experience in shaping cognitive preferences.

To explore whether the bias extended beyond language, participants also performed similar tasks with non-linguistic, sound stimuli. The data from this study showed that neither Basque-Spanish bilinguals, nor Spanish monolinguals revealed any type of preference (i.e., suffix or prefix) on the non-linguistic material. This further reinforces the idea that the suffixing preference is rooted in language-specific mechanisms rather than general cognitive processes.

Ordin’s study represents a significant step forward in resolving the suffixing bias debate. By showing that the suffixing bias is limited to linguistic material and modulated by native language morphology, the study provides strong evidence for a language-specific origin of the bias, and it shows the adaptability of human cognition to accommodate the structural properties of different languages, challenging assumptions about universal preferences.

In sum, the suffixing bias highlights the intricate interplay between cognition, language, and culture. It reminds us that human language, while governed by universal principles, is also deeply shaped by the unique properties of individual linguistic systems and by the broader social and cultural contexts in which these systems develop. As research continues, studies like Ordin’s will help us better understand not only why languages look the way they do but also how our brains make sense of them. For now, the suffixing bias remains a testament to the remarkable adaptability of human cognition—and a reminder of how much we have yet to learn about the language that defines us.

Affixation patterns in native language and sequence processing by statistical learning mechanisms

Authors biography: Inês C. Ferreira is a PhD candidate in the LMD Lab at the Faculty of Psychology and Educational Sciences, University of Coimbra, under the supervision of Dr. Leona Polyanskaya and Dr. Mikhail Ordin. Her current research investigates metacognition and decision-making, studying the ways we reflect on and navigate our choices. Simultaneously, she explores the interplay between language acquisition and the brain.      

                                  

References:

Dryer, M. S. (2013). Prefixing vs. suffixing in inflectional morphology. In M. S. Dryer &          M. Haspelmath (Eds.), The world atlas of language structures online. Leipzig, Germany: Max Planck Institute for Evolutionary Anthropology.

Hupp, J. M., Sloutsky, V. M., & Culicover, P. W. (2009). Evidence for a domain-general. mechanism underlying the suffixation preference in language. Language and Cognitive Processes, 24(6), 876–909. https://doi.org/10.1080/01690960902719267

Martin, A., & Culbertson, J. (2020). Revisiting the suffixing preference: native-language affixation patterns influence perception of sequences. Psychological Science 31(9), 1107-1116.

Ordin, M. (2025). Affixation patterns in native language and sequence processing by statistical learning mechanisms. Evolutionary Human Sciences.